This week was slightly truncated because of the Bank Holiday, and allowed some catching up in Swindon. I went to listen to the first speech by Dr Vince Cable (who has a PhD in economics and used to teach the subject at Glasgow) on the priorities for economic growth. Notwithstanding the present rather gloomy economic position, statements such as “BIS is the Ministry for science, and science is a vital public good” give one grounds for optimism.

I have blogged before about the fact that many things we learned when young (in science and elsewhere) are not in fact true (or may subsequently have been shown not to be). One such myth is that after adolescence one has a fixed number of brain cells and they are not regenerated in adulthood (indeed, alcohol was said to kill them by the thousand). While the very existence of brain tumours shows that adult CNS cells can divide, it does not tell us whether they normally do so. Happily, using methods such as bromodeoxyuridine (ChEBI) labelling and immunocytochemistry, it is now recognized that there is in fact considerable turnover (neurogenesis) in adults – see e.g. reviews by Gould, by Zhao et al., and by Imayoshi et al. This has many beneficial implications for healthy ageing.

Changes in both wealth and weight are determined by the difference between one’s income and expenditure of money or calories. Unlike Mr Micawber, for whom an excess of income over expenditure resulted in happiness, for those seeking to lose weight the opposite must be the case. Clearly one can beneficially attack both sides of the equation (eat less, exercise more), albeit we all know people who can eat as much as they like and do not put on weight. Regarding the burning of energy, I had always understood that this was mainly determined by variation in the basal (or resting) metabolic rate, with even quite severe exercise burning calories (or body mass) in comparatively small amounts. A visit to Sport, Health and Exercise Science at the University of Bath (among many other interesting projects I saw there) told me that this is essentially not the case. While there is considerable uncertainty regarding how much exercise is good for you, and even what that means, modern methods of non-invasive in vivo monitoring of energy expenditure show that sustained physical activity – whether by formal exercise or otherwise – does undoubtedly account for much of the variance in energy expenditure between individuals.